Edit: Changing my review to 5 stars because of how amazing the company is
They reached out and apologized for it not working for a woman's mountain bike and not only refunded my purchase, but sent me another version they had for me to try to see if it would work. I'm going to test it out once the weather gets better but even if it doesn't quite work out I'd 100% recommend this company because of how good their customer service is
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Original Review:
I really really wanted to love this because I can totally see how it would work but unfortunately even though it says it works on mountain bikes, it doesn't work on women's mountain bikes. No matter how I tighten it the seat always slides back. But if you try it on a men's it should work as long as you install it correctly.

If you install this correctly it works great. Unfortunately, it doesn’t come with installation instructions. I am an engineer and avid bike mechanic so I got it to work well for me.
Step 1: leave all hardware loose and seat uninstalled.
Step 2: fit to top tube of bike and tighten large Allen key in seat mount cylinder while squeezing the assembly together.
Step 3: screw the foot pad backing nuts so they give plenty of space to install the foot pads tight around the frame.
Step 4: install the foot pads making sure they squeeze the bottom tube tight. Ensure proper location of assembly on frame (not to close to bike seat and not to close to handlebars).
Step 5: tighten foot pad backing nuts.
Step 6: tighten four lock nuts on upper assembly. NOTE: Do NOT over-tighten these nuts. If the top assembly is still loose after installing the quick release cross pin you need to loosen all hardware and start assembly over from the beginning. The main Allen key bolt in the seat mount cylinder is responsible for gripping the top tube correctly.
Step 7: install quick release cross bolt so it is slightly closer to top tube than bottom tube.
Step 8: ensure proper angle of kid seat by loosening seat clamp prior to installation and adjusting angle and checking fit.
Step 9: install kid seat and tighten seat clamp nuts.
Step 10: install kid handle bars onto bike handlebars using rubber inserts as needed to get correct fit.
Step 11: place child on assembly and adjust fit as necessary.
Ensure assembly does not move when installation is complete or it could damage your bike frame, paint, or your child.
Have fun!!!

I recently purchased the Kid Bike Seat, and I must say, it has been a fantastic addition to our biking adventures. Overall, I thoroughly enjoyed this product. My 4-year-old girl absolutely loves riding on daddy's bike now, and it has become a fun bonding experience for us.
One thing that impressed me was how easy it was to assemble the bike seat. It didn't require any complex tools or hours of frustration, making it a hassle-free experience. Additionally, the build quality of this seat seems sturdy and durable, which gives me confidence that it will last through many rides to come.
In summary, I'm genuinely happy with my purchase of the Kid Bike Seat. It has brought joy to our family outings, and its ease of assembly and apparent durability make it a great investment for any parent who loves biking with their little one.

EDIT: The seller contacted me and offered a resolution. Updated to 5 stars because their customer service is great! ⭐️⭐️⭐️⭐️⭐️
We really want to love this bike seat! We purchased it for our 3 year old so that he can join the rest of the family on trail rides. Our seat did not come with instructions and while the mounting parts are secure on the frame of my bike, the seat wobbles and spins completely around – it actually fell off yesterday while i was lifting my son onto it. We've taken it off and put it back on, trying everything we can to keep it from wobbling without luck. Unfortunately we will be returning it unless we can find a way to get more secure.

Wow. Can't beat its price. It fits my XL frame 29er Giant dual suspension bicycle. Not alot of room but just enough to make it comfortable and secure. Just be careful of the all thread under the frame. May rub and scratch. I used an old patch so it does not scratch the frame. Good buy! Def recommend it.

I believe I was partially scammed, I received most of the parts, except for the seat and the handles, the rest of the stuff in box were random bolts, some rubber puck looking thing, a plastic chain and a white make up bag or something like that.

You get what you pay for. It’s decent for the money bust rust quickly, metal components can easily come into contact with bike and scratch paint, the foot peg strap broke off from the mounting point on the peg, not the actual strap surprisingly. It’s a quarter of the price of the fancy one and it shows. But it got the job done to confirm my toddlers interest before buying the expensive seat attachment.

I think it was probably great if you has the right bike. I had a thicker framed women's mountain bike and it didn't fit the width of the frame not the slant. But it looked functional, small profile, not flimsy, and did the job.